The present invention relates to a technique for providing a service using map data to a user and, in particular, to a technique for distributing data to update map data stored on a terminal device.
Services using map data such as a navigation service for motor vehicles or pedestrians are widely provided. Map data is normally displayed on the screen of a terminal possessed by a user who receives such a service. Besides, by displaying various kinds of additional information overlaying the map, convenience of users can be improved. A typical example of additional information is so-called VICS (Vehicle Information and Communication System, a registered trademark) information, that is, information on traffic congestion and restriction among others. Other examples of additional information that is beneficial for users are information on facilities recommended to users, weather information (for example, information on a road that may be flooded due to a so-called guerilla-like torrential rain or the like), etc.
On the other hand, map information stored on a terminal is updated to reflect a change due to new construction, abolition, or the like of a real road, facility, or the like. In this regard, although map data over a widespread area (e.g., all over Japan) may be updated in a lump, such update takes considerable time because of a large amount of data to be updated. Thus, in late years, inter alfa, a method in which update is confined to a partition for which update is required and update is performed on a per-partition basis (see, e.g., Japanese Unexamined Patent Application Publication No. 2003-65770) and a method of updating only data for differences (differences between old version map data and new version map data) for each partition are known.